Wet compression centrifugal compressor and air inlet compression control method

Abstract

The invention discloses a wet compression centrifugal compressor and an air inlet compression control method.The compressor comprises an impeller and an impeller cover, an air inlet flow channel is formed between the impeller cover and the impeller, water spraying holes used for spraying liquid into the air inlet flow channel for cooling are formed in the impeller cover in the air inlet flowing direction, and the water spraying holes are evenly distributed in the surface of the impeller cover; a spray head is correspondingly arranged in each water spray hole, each spray head is communicated with a water quantity server through a pipeline, a regulating valve used for controlling the water spray quantity is independently connected to the communication position, and the water spray quantity at the water spray holes is controlled through the water quantity server; the air inlet channel is arranged in the air flow direction; the main vaporization water spraying holes and the supplementary vaporization water spraying holes are formed in the wheel cover, the water spraying amount can be flexibly adjusted, it is guaranteed that air in a gas compression channel is close to saturated wet air, the wheel cover is suitable for an inverter compressor, and the power saving amount cannot be obviously reduced along with the change of the operation working condition of the compressor.

Description

Technical Field

[0001] The invention relates to the technical field of centrifugal compressors, and in particular to a wet compression centrifugal compressor and an intake compression control method. Background Art

[0002] Centrifugal compressors are widely used in industrial production due to their advantages such as high single-stage pressure ratio and wide operating range. However, their power consumption is greater than that of oil-injected screw compressors of the same level at higher pressure levels. This is mainly because centrifugal compressors are usually adiabatic compression, and the power consumption of the compression process is relatively large.

[0003] The concept of wet compression was proposed in the field of gas turbines in the last century. Liquid droplets are sprayed into the compression process to absorb heat through the evaporation of the droplets to reduce the compression work required for the compression process. The current wet compression technology can be mainly divided into three categories: inlet water spray, interstage water spray and blade water spray. The compressor inlet water spray has a simple structure, but the liquid spray gasification effect is difficult to ensure the optimal vaporization condition during the entire compression process. In addition, the inlet water spray will cause the compressor intake distortion and affect the efficiency, and there is a risk of freezing when the inlet temperature is too low under winter conditions. Interstage water spray can reduce the intake temperature of the subsequent stage and avoid the freezing problem, but its work saving is smaller than that of inlet water spray. The impeller water spray has a better actual effect, but its structural process is very complicated and it is difficult to apply to civilian products. In addition, unlike the gear speed increase compressor of the last century, more and more centrifugal compressors currently use variable frequency motors to adapt to more working conditions. The traditional fixed water spray device is difficult to adapt to the changes in winter and summer, large and small load conditions, which makes the work saving of water spray wet compression significantly lower than the ideal optimal situation, and there is even a risk of shutdown caused by excessive water spray and low gasification degree. Summary of the invention

[0004] Technical purpose: In view of the shortcomings of the impeller water spraying of the above-mentioned existing centrifugal compressors, the present invention discloses a wet compression centrifugal compressor and an intake compression control method capable of flexibly adjusting the water spraying amount.

[0005] Technical solution: To achieve the above technical objectives, the present invention adopts the following technical solution: A wet compression centrifugal compressor comprises an impeller and a wheel cover, an inlet airflow passage is formed between the wheel cover and the impeller, water spray holes for spraying liquid into the inlet airflow passage for cooling are arranged in the inlet airflow direction on the wheel cover, the water spray holes are evenly distributed along the surface of the wheel cover, a nozzle is correspondingly arranged in each water spray hole, the nozzles are connected to a water volume server through a pipeline, a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole is controlled by the water volume server; along the airflow direction of the inlet airflow passage, the water spray holes comprise a main vaporization water spray hole located near the inlet end of the inlet airflow passage and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spray according to the relative humidity of the gas, the nozzle aperture in the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole.

[0006] Preferably, in the present invention, along the gas flow direction of the inlet flow duct, the axis of the water spray holes near the gas inlet and outlet ends is perpendicular to the wall surface of the inlet flow duct; the axis of the water spray holes in the middle area is parallel to the wall surface of the inlet flow duct, spraying liquid to cool the gas while suppressing leakage of the impeller blade tip gap.

[0007] Preferably, the present invention provides a humidity measuring point for detecting the humidity of the gas behind the corresponding water spray hole along the axial direction of the inlet air passage.

[0008] Preferably, the water spray holes in the same axial plane of the wheel cover of the present invention are arranged at 5%, 30% and 70% of the length of the intake air passage along the axial direction of the intake air passage, wherein the water spray holes at the 5% length position serve as main vaporization water spray holes, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes.

[0009] Preferably, the humidity measuring points of the present invention are arranged at 15%, 45% and 85% length positions of the axis of the intake air passage.

[0010] Preferably, the water spraying positions of the water spraying holes in front of the humidity measuring point positions of the present invention are staggered in the circumferential direction.

[0011] Preferably, the axis of the water spray hole at the 30% length position of the present invention is parallel to the wall surface of the air inlet channel, and the axis of the water spray hole at the 70% length position is perpendicular to the air inlet channel.

[0012] The present invention discloses an intake air compression control method according to the above-mentioned wet compression centrifugal compressor, comprising the steps of: S01, dividing the centrifugal compressor into a normal operation area and a near-surge area according to the operating conditions, and setting the corresponding water injection amount, and determining the current operating area of ​​the compressor according to the flow rate and pressure parameters of the centrifugal compressor during operation; S02, determining the corresponding maximum total water spray flow rate according to the suction flow rate; S03. Within the range below the maximum total water spray flow rate, the water spray flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measuring point set on the wheel cover. The water spray flow rate of the nozzle is adjusted according to the monitoring results, so that the humidity of the gas downstream along the air intake direction is close to 99%.

[0013] Preferably, in step S02 of the present invention, when water is initially sprayed, if the operating area of ​​the centrifugal compressor is in the normal operating area, the maximum total water spray flow rate is set to 3% of the suction flow rate; if the operating area of ​​the centrifugal compressor is in the near-surge area, the maximum total water spray flow rate is set to 1% of the suction flow rate.

[0014] Preferably, in step S03 of the present invention, when the water spraying amount of the nozzle is adjusted according to the monitoring result of the humidity measuring point, when the average humidity value monitored by the humidity measuring point is lower than 95% or higher than 99%, the total water spraying flow rate is increased or decreased accordingly, and the gas humidity is controlled so that the average humidity value is in the range of 95%-99%; when the average humidity value is in the range of 95%-99%, the flow rate of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the inlet air duct, so that the downstream gas humidity approaches 99%.

[0015] Beneficial effects: The wet compression centrifugal compressor and the intake air compression control method disclosed in the present invention have the following beneficial effects: 1. The present invention can flexibly adjust the water spraying amount by arranging the main vaporization water spraying hole and the supplementary vaporization water spraying hole on the wheel cover to ensure that the gas humidity meets the demand. It is suitable for variable frequency compressors, and the power saving will not decrease significantly with the change of the compressor operating conditions.

[0016] 2. According to the profile of the intake air duct, the water spray holes near the inlet and outlet areas of the present invention are arranged with their axes perpendicular to the wall of the intake air duct, so that liquid droplets can be sent into the interior of the intake air duct for sufficient vaporization and cooling. The axes of the water spray holes in the middle area are nearly parallel to the wall of the intake air duct, so that leakage of the blade tip clearance can be suppressed while supplementing vaporization and cooling of the gas, thereby improving the operating efficiency and operating range of the centrifugal compressor.

[0017] 3. The present invention sets a humidity measuring point to monitor the gas humidity and realizes real-time feedback control of the water spraying amount, which can improve the control accuracy, make the relative humidity of the air always close to 100% during the compression process, and the simulated power saving can reach 5%.

[0018] 4. The humidity measuring point of the present invention is arranged behind the water spraying position and is offset from the water spraying point in the circumferential direction, which can improve the accuracy of gas humidity monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the position structure of the compressor impeller of the present invention; Figure 2 This is a schematic diagram of the structure of the roulette disk of the present invention; Among them, 1-impeller, 2-impeller cover, 3-inlet air duct, 4-water spray hole, 5-humidity measuring point. DETAILED DESCRIPTION

[0021] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are set forth herein below. Each embodiment and example is provided by way of explanation of the apparatus, composition and materials of the present disclosure, rather than limitation. On the contrary, the following description provides a convenient illustration of an exemplary embodiment for implementing the present disclosure. In fact, it will be clear to those skilled in the art that various modifications and variations may be made in the teachings of the present disclosure without departing from the scope or spirit of the present disclosure.

[0022] like Figure 1 and Figure 2 As shown, a wet compression centrifugal compressor, the improvement mainly involves the improvement of the water spray structure at the compressor impeller position, so Figure 1 and Figure 2 A partial view of the impeller position is provided; it includes an impeller 1 and a wheel cover 2, an inlet air passage 3 is formed between the wheel cover 2 and the impeller 1, a water spray hole 4 for spraying liquid into the inlet air passage 3 for cooling is arranged on the wheel cover 2 in the direction of the inlet air flow, the water spray holes 4 are evenly distributed along the surface of the wheel cover 2, a nozzle is correspondingly arranged in each water spray hole 4, the nozzles are connected to the water volume server through a pipeline, a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole 4 is controlled by the water volume server; along The air flow direction of the inlet airflow channel 3, the water spray hole includes a main vaporization water spray hole located near the inlet end of the inlet airflow channel and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spray according to the relative humidity of the gas. The nozzle aperture of the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole. The nozzle aperture of the main vaporization water spray hole is large, and larger droplets can be produced to extend into the inlet airflow channel to fully vaporize and cool the gas. In the embodiment of the present invention, the nozzle diameter of the main vaporization water spray hole is 20 , the nozzle diameter of the supplementary vaporization water spray hole is 10 .

[0023] In the present invention, the axis of the water spray hole 4 located along the gas flow direction of the inlet flow channel 3 and close to the gas inlet and outlet ends is perpendicular to the wall of the inlet flow channel, so that the liquid droplets can penetrate into the inlet flow channel to ensure the heat exchange effect; the axis of the water spray hole 4 in the middle area is parallel to the wall of the inlet flow channel, where the curvature is relatively large, and part of the air flow will flow out through the fitting gap between the impeller and the wheel disc, thereby affecting the efficiency of the compressor. The water spray hole of the present invention is arranged in a manner parallel to the wall of the inlet flow channel, which can realize the liquid spray cooling of the gas while suppressing the leakage of the impeller blade tip gap, thereby improving the operating efficiency and operating range of the compressor.

[0024] To achieve real-time monitoring of humidity, Figure 2 As shown, the present invention sets a humidity measuring point 5 for detecting the humidity of the gas behind the corresponding water spray hole 4 along the axial direction of the inlet air flow channel 3. The humidity of the gas after each water spray hole 4 sprays water is detected through the humidity measuring point 5. In order to improve the accuracy of the detection, the water spraying positions of the water spray holes 4 in front of the humidity measuring point 5 corresponding to the position of the humidity measuring point 5 are staggered in the circumferential direction. The staggering angle is preferably 45°. An electronic hygrometer is installed for detection. After spraying water, the vaporized and cooled gas will flow to the area where the humidity measuring point 5 is located, so as to obtain accurate humidity data in the vaporized gas.

[0025] The water spray holes 4 of the present invention, which are located in the same axial plane of the wheel cover 2, are arranged at 5%, 30% and 70% of the length of the intake air channel along the axial direction of the intake air channel, wherein the water spray holes at the 5% length position serve as main vaporization water spray holes, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes. The axis of the water spray hole at the 30% length position is parallel to the wall of the intake air channel, and the axis of the water spray hole at the 70% length position is perpendicular to the intake channel. There are 12 water spray holes in total, which are distributed at 90° intervals along the circumferential direction of the wheel cover 2. The corresponding humidity measuring points 5 are arranged at 15%, 45% and 85% of the length of the axis of the intake air channel to detect the humidity of the gas after the corresponding front water spray holes spray water.

[0026] The present invention discloses an intake air compression control method according to the above-mentioned wet compression centrifugal compressor, comprising the steps of: S01, dividing the centrifugal compressor into a normal operation area and a near-surge area according to the operating conditions, and setting the corresponding water injection amount, and determining the current operating area of ​​the compressor according to the flow rate and pressure parameters of the centrifugal compressor during operation; S02. Determine the corresponding maximum total water injection flow rate according to the suction flow rate; when initially spraying water, if the operating area of ​​the centrifugal compressor is in the normal operating area, the maximum total water injection flow rate is set to 3% of the suction flow rate; if the operating area of ​​the centrifugal compressor is in the near-surge area, the maximum total water injection flow rate is set to 1% of the suction flow rate.

[0027] S03. Within the range below the maximum total water spray flow rate, the water spray flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measuring point set on the wheel cover. The water spray flow rate of the nozzle is adjusted according to the monitoring results, so that the humidity of the gas downstream along the air intake direction is close to 99%.

[0028] In step S03 of the present invention, when the amount of water sprayed by the nozzle is adjusted according to the monitoring result of the humidity measuring point, when the average humidity value monitored by the humidity measuring point is lower than 95% or higher than 99%, the total amount of water spray is increased or decreased accordingly, and the gas humidity is controlled so that the average humidity value is in the range of 95%-99%; when the average humidity value is in the range of 95%-99%, the flow of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the intake air flow channel, so that the gas humidity downstream is close to 99%. The control method of the present invention can realize the ideal wet compression process of the compressor, that is, the evaporation of the water sprayed during the compression process makes the relative humidity of the air in the compression process always close to 100%, and the power saving can reach 5% through computational fluid dynamics simulation, and the amount of water sprayed at each point can be adjusted in real time, which is suitable for variable frequency compressors, and the power saving does not decrease significantly with the change of the compressor operating conditions, thereby ensuring efficiency.

Claims

1. A wet compression centrifugal compressor, characterized in that: The invention comprises an impeller (1) and a wheel cover (2), wherein an inlet flow channel (3) is formed between the wheel cover (2) and the impeller (1), and water spray holes (4) for spraying liquid into the inlet flow channel (3) for cooling the air are arranged on the wheel cover (2) in the direction of the inlet flow, and the water spray holes (4) are evenly distributed along the surface of the wheel cover (2), and a nozzle is correspondingly arranged in each water spray hole (4), and the nozzles are connected to a water volume server through a pipeline, and a regulating valve for controlling the water spray volume is separately connected at the connection point, and the water spray volume at the water spray hole (4) is controlled by the water volume server; along the air flow direction of the inlet flow channel (3), the water spray holes include a main vaporization water spray hole located near the inlet end of the inlet flow channel and a supplementary vaporization water spray hole located inside the main vaporization water spray hole for supplementary water spray according to the relative humidity of the gas, and the nozzle aperture in the main vaporization water spray hole is larger than the nozzle aperture of the supplementary vaporization water spray hole.

2. A wet compression centrifugal compressor according to claim 1, characterized in that: Along the gas flow direction of the inlet flow channel (3), the axes of the water spray holes (4) near the gas inlet and outlet ends are perpendicular to the wall surface of the inlet flow channel; the axes of the water spray holes (4) in the middle area are parallel to the wall surface of the inlet flow channel, spraying liquid to cool the gas while suppressing leakage of the impeller blade tip gap.

3. A wet compression centrifugal compressor according to claim 2, characterized in that: A humidity measuring point (5) for detecting the humidity of the gas is arranged behind the corresponding water spray hole (4) along the axial direction of the inlet air flow passage (3).

4. A wet compression centrifugal compressor according to claim 3, characterized in that: The water spray holes (4) located in the same axial plane of the wheel cover (2) are arranged at 5%, 30% and 70% of the length of the intake air passage along the axial direction of the intake air passage, wherein the water spray holes at the 5% length position serve as main vaporization water spray holes, and the water spray holes at the 30% and 70% length positions serve as supplementary vaporization water spray holes.

5. A wet compression centrifugal compressor according to claim 4, characterized in that: The humidity measuring points (5) are arranged at 15%, 45% and 85% length positions of the axis of the intake air passage.

6. A wet compression centrifugal compressor according to claim 4 or 5, characterized in that: The water spraying positions of the water spraying holes (4) in front of the positions of the humidity measuring points (5) are staggered with each other in the circumferential direction.

7. A wet compression centrifugal compressor according to claim 4, characterized in that: The axis of the water spray hole at the 30% length position is parallel to the wall of the intake air channel, and the axis of the water spray hole at the 70% length position is perpendicular to the intake air channel.

8. An intake air compression control method for a wet compression centrifugal compressor according to any one of claims 1 to 7, characterized in that: Includes steps: S01, dividing the centrifugal compressor into a normal operation area and a near-surge area according to the operating conditions, and setting the corresponding water injection amount, and determining the current operating area of ​​the compressor according to the flow rate and pressure parameters of the centrifugal compressor during operation; S02, determining the corresponding maximum total water spray flow rate according to the suction flow rate; S03. Within the range below the maximum total water spray flow rate, the water spray flow rate of the nozzle is distributed through the water volume servo, and the humidity of the gas is monitored through the humidity measuring point set on the wheel cover. The water spray flow rate of the nozzle is adjusted according to the monitoring results, so that the humidity of the gas downstream along the air intake direction is close to 99%.

9. The intake air compression control method of a wet compression centrifugal compressor according to claim 8, characterized in that: In step S02, when water is initially sprayed, if the operating area of ​​the centrifugal compressor is in the normal operating area, the maximum total water spray flow rate is set to 3% of the suction flow rate; if the operating area of ​​the centrifugal compressor is in the near-surge area, the maximum total water spray flow rate is set to 1% of the suction flow rate.

10. The intake air compression control method of a wet compression centrifugal compressor according to claim 8, characterized in that: In step S03, when the water spraying amount of the nozzle is adjusted according to the monitoring result of the humidity measuring point, when the average relative humidity monitored by the humidity measuring point is lower than 95% or higher than 99%, the total water spraying flow rate is increased or decreased accordingly, and the gas humidity is controlled so that the average humidity value is in the range of 95%-99%; when the average humidity value is in the range of 95%-99%, the flow rate of the nozzle is adjusted according to the gas humidity monitored by the humidity measuring point downstream of the inlet air duct, so that the downstream gas humidity approaches 99%.

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